Engineering and detection of light scattering directionalities in dewetted nanoresonators through dark-field scanning microscopy.

Dewetted, SiGe nanoparticles have been successfully exploited for light management in the visible and near-infrared, although their scattering properties have been so far only qualitatively studied. Here, we demonstrate that the Mie resonances sustained by a SiGe-based nanoantenna under tilted illumination, can generate radiation patterns in different directions. We introduce a novel dark-field microscopy setup that exploits the movement of the nanoantenna under the objective lens to spectrally isolate Mie resonances contribution to the total scattering cross-section during the same measurement. The knowledge of islands' aspect ratio is then benchmarked by 3D, anisotropic phase-field simulations and contributes to a correct interpretation of the experimental data.

Fully Integrated Silicon Photonic Erbium-Doped Nanodiode for Few Photon Emission at Telecom Wavelengths.

Recent advancements in quantum key distribution (QKD) protocols opened the chance to exploit nonlaser sources for their implementation. A possible solution might consist in erbium-doped light emitting diodes (LEDs), which are able to produce photons in the third communication window, with a wavelength around 1550 nm. Here, we present silicon LEDs based on the electroluminescence of Er:O complexes in Si. Such sources are fabricated with a fully-compatible CMOS process on a 220 nm-thick silicon-on-insulator (SOI) wafer, the common standard in silicon photonics. The implantation depth is tuned to match the center of the silicon layer. The erbium and oxygen co-doping ratio is tuned to optimize the electroluminescence signal. We fabricate a batch of Er:O diodes with surface areas ranging from 1 µm × 1 µm to 50 µm × 50 µm emitting 1550 nm photons at room temperature. We demonstrate emission rates around 5 × 106 photons/s for a 1 µm × 1 µm device at room temperature using superconducting nanowire detectors cooled at 0.8 K. The demonstration of Er:O diodes integrated in the 220 nm SOI platform paves the way towards the creation of integrated silicon photon sources suitable for arbitrary-statistic-tolerant QKD protocols.

Large-Area Nanocrystalline Caesium Lead Chloride Thin Films: A Focus on the Exciton Recombination Dynamics.

Caesium lead halide perovskites were recently demonstrated to be a relevant class of semiconductors for photonics and optoelectronics. Unlike CsPbBr3 and CsPbI3, the realization of high-quality thin films of CsPbCl3, particularly interesting for highly efficient white LEDs when coupled to converting phosphors, is still a very demanding task. In this work we report the first successful deposition of nanocrystalline CsPbCl3 thin films (70-150 nm) by radio frequency magnetron sputtering on large-area substrates. We present a detailed investigation of the optical properties by high resolution photoluminescence (PL) spectroscopy, resolved in time and space in the range 10-300 K, providing quantitative information concerning carriers and excitons recombination dynamics. The PL is characterized by a limited inhomogeneous broadening (~15 meV at 10 K) and its origin is discussed from detailed analysis with investigations at the micro-scale. The samples, obtained without any post-growth treatment, show a homogeneous PL emission in spectrum and intensity on large sample areas (several cm2). Temperature dependent and time-resolved PL spectra elucidate the role of carrier trapping in determining the PL quenching up to room temperature. Our results open the route for the realization of large-area inorganic halide perovskite films for photonic and optoelectronic devices.

Engineering of the spin on dopant process on silicon on insulator substrate.

We report on a systematic analysis of phosphorus diffusion in silicon on insulator thin film via spin-on-dopant process (SOD). This method is used to provide an impurity source for semiconductor junction fabrication. The dopant is first spread into the substrate via SOD and then diffused by a rapid thermal annealing process. The dopant concentration and electron mobility were characterized at room and low temperature by four-probe and Hall bar electrical measurements. Time-of-flight-secondary ion mass spectroscopy was performed to estimate the diffusion profile of phosphorus for different annealing treatments. We find that a high phosphorous concentration (greater than 1020 atoms cm-3) with a limited diffusion of other chemical species and allowing to tune the electrical properties via annealing at high temperature for short time. The ease of implementation of the process, the low cost of the technique, the possibility to dope selectively and the uniform doping manufactured with statistical process control show that the methodology applied is very promising as an alternative to the conventional doping methods for the implementation of optoelectronic devices.